Method of bonding material having a low coefficient of friction to a substrate

ABSTRACT

Method of bonding sheet material having a very low coefficient of friction to a substrate such as rubber, felt or the like, which comprises providing, as an uncured bonding material, cotton textile fabric impregnated with a thermosetting general purpose phenolic resin; buffing the surface of the substrate; placing thereon a ply of the uncured bonding material; placing the lowcoefficient material upon the bonding layer and then vulcanizing the assembly.

United States Patent Palfreyman 1 May 16, 1972 [54] METHOD OF BONDINGMATERIAL 3,403,071 9/1968 Perry et al. ..l56/335 HAVING A LOWCOEFFICIENT 0F 33%;"; 2x32: FRICTION TO A SUBSTRATE 72 In entor: DonaldH. Palfre man Dedh M 1 v y am ass Primary Examiner-Leland A. Sebastian[73] Assignee: Fabreeka Products Company, Boston, Assistant Examiner-B.H. Hunt Mass. Att0rneyRoberts, Cushman & Grover [22] Filed: July 18,1969 57 ABSTRACT PP N01 843,086 Method of bonding sheet material havinga very low coefficient of friction to a substrate such as rubber, feltor the like, which comprises providing, as an uncured bonding material,[52] US. Cl 156/256, 156/153, 156/267, Cotton textile fabric impregnatedwith a thermosetting genera] 156/3, 156/335 purpose phenolic resin;buffing the surface of the substrate; [51 Int. Cl .332) 31/12 i th r aly Qfthe uncured bonding material; placing Fi l Of Search 256 thelow-coefficient material upon the bonding layer and then vulcanizing theassembly. 56 R f C"! 1 ed 5 Claims, 2 Drawing Figures UNITED STATESPATENTS 3,501,360 3/1970 Mancel ..l56/153 SUEJTERTE W/zZ/ZBER Buff50357159975 BOND/N6 3 y MflTf/P/HL BOND/N6 RTE lfl k-ug ,3

r I 51/25 265 5 5' I I M/ITfP/fll.

r 1 l Vl/l CHNI I I (Up/N6 l Press L r '1 1 new: I 176! 1% l par; 0 4.EDGE 2 METHOD OF BONDING MATERIAL HAVING A LOW COEFFICIENT OF FRICTIONTO A SUBSTRATE BACKGROUND OF THE INVENTION Difficulty has beenexperienced in bonding a material having a low coefiicient of friction,for specific example, the fiuoroplastie film known as Teflonmanufactured by E. l. du- Pont de Nemours Co., which is insoluble inmost common solvents, since there are no solvents for Teflonfluoroplastic, techniques other than conventional solvent cementing mustbe used, duPont recommends that the surfaces of parts fabricated fromthe fluoroplastic first be modified with strong etching solutions tomake them receptive to conventional selfcuring adhesive systems." ModernPlastics Encylcopedia, Vol. 45, No. 1A, Page 995.

The present invention, as the result of much experimentation, provides anovel method of and means for so uniting such a surface material, havinga low coefficient of friction, as for example, Teflon to a substrate ofsuch material as rubber, felt, laminated fabrics, thereby providing anacceptable and permanent bond.

In the annexed drawing:

FIG. 1 is a flow sheet diagrammatically illustrating the several stepsof the present method; and

FIG. 2 is a diagrammatic section illustrating the completed material.

Assuming, for example, that rubber is the material of the substrate towhich the low-coefficient-of-friction material is to be bonded, thefirst step in the present method is to buff the surface of the rubbersubstrate to provide a matte texture. There is then provided a ply ofuncured bonding material, which may, for example, comprise cottoncanvas, of a weight in excess of 4 ounces per square yarn and of a yarncount of approximately 56 warp yarns and 24 double filling yarns perinch, and which has been impregnated with a thermosetting phenolic resinto the extent that, if the impregnated material were cured at thisstage, the resin would impart a surface gloss to the textile fabric. Theselected resin should have substantial mechanical strength, dimensionalstability and corrosion-resistance when cured and desirably the abilityto sustain heavy loads even when exposed to high temperatures. A generalpurpose phenolic resin would have these characteristics. As indicativeof these characteristics of this type of resin, note the followingquotation:

Industrial laminates are those materials which are intended for suchapplications as gears, cams, roll neck bearings, structural shapes,components for switchgear, and so on. General purpose phenolic varnishesare usually used as the impregnant in laminates going into suchapplications. 1968 Modern Plastics Encyclopedia Vol. 45/No. lA Page184."

From the impregnated but uncured bonding material, a piece is cut of asize such as to cover the rubber substrate. This piece of bondingmaterial is then placed upon the bufied surface of the substrate, and apiece of the material (having the low coefficient of friction) is placedupon the bonding layer, said piece preferably being of a size such thatit overlaps the bonding material by approximately one-fourth inch allaround. The thus assembled plies are then placed in a vulcanizing pressor equivalent apparatus and subjected to a pressure of approximately 300psi and kept at a temperature of 290 F. for approximately 15 minutes.The cured material is then removed from the press and allowed to cool.its edges are then trimmed to the final desired dimensions and thetrimmed edges are buffed to provide a finished appearance.

While hereinabove a specific fluoroplastic film has been mentioned asthe material having a low coefficient of friction, it will be understoodthat this is merely by way of example and as a specific illustration ofthe utility of the present invention.

1 claim:

1. A method of bonding a surface material comprised of fluoroplasticfilm having a low coefficient of friction to a rubber substrate whichcomprises as steps; buffing the surface of the substrate, providingbonding material comprising textile fabric impregnated with an uncuredphenolic resin, interposing a piece of the bonding material between thesubstrate and the surface material and vulcanizing the assembly thereby,while curing the resin, to permanently bonding the surface material tothe substrate.

2. The method according to claim 1, further characterized in that, incuring the bonding material, the assembled parts are subjected to apressure of approximately 300 psi at a temperature of the order of 290F., and maintaining said pressure until the bonding material has beencured.

3. The method according to claim 2, and wherein the surface material isa fluorocarbon sheet, further characterized in that the textile fabricin the bonding material is a cotton canvas of a weight in excess of 4ounces per square yard and of a yarn count of approximately 56 warpyarns and 24 double filling yarns per inch.

4. The method according to claim 1, further characterized in cutting thesurface material to a size such that when placed upon the bonding layerit overlaps the latter approximately one-fourth inch all around, coolingthe cured material after removal from the press, and then trimming theedges to the final desired dimensions.

5. The method according to claim 4, further characterized in buffing theedges after trimming.

2. The method according to claim 1, further characterized in that, incuring the bonding material, the assembled parts are subjected to apressure of approximately 300 psi at a temperature of the order of 290*F., and maintaining said pressure until the bonding material has beencured.
 3. The method according to claim 2, and wherein the surfacematerial is a fluorocarbon sheet, further characterized in that thetextile fabric in the bonding material is a cotton canvas of a weight inexcess of 4 ounces per square yard and of a yarn count of approximately56 warp yarns and 24 double filling yarns per inch.
 4. The methodaccording to claim 1, further characterized in cutting the surfacematerial to a size such that when placed upon the bonding layer itoverlaps the latter approximately one-fourth inch all around, coolingthe cured material after removal from the press, and then trimming theedges to the final desired dimensions.
 5. The method according to claim4, further characterized in buffing the edges after trimming.